Skin infection is commonly treated with antimicrobial agents orally and/or topically. Topical treatment is preferred because it can minimize any potential systemic adverse effects of drugs and it is also less expensive. Acne, mainly caused by P. acnes, and warts (i.e., verruca) caused by human papillomavirus, are two common, potentially serious skin infectious diseases (“Current Medical Diagnosis and Treatment” by L. M. Tierney, Jr. et al., Lange Medical Books, NY, 2004, pp. 111-113 and 123-125; “Andrews' Diseases of the Skin, Clinical Dermatology” by R. B. Odom et al., Philadelphia, 2000, pp. 284-306 and 509-519.) Topical acne treatment commonly includes prescription-required antibiotics (such as erythromycin and clindamycin) and potent retinoids. The effectiveness of the above treatment method does not appear to be satisfactory since many weeks or months of continuous daily treatment are generally required. In one study, for example, only about 50% of patients showed satisfactory responses after 12 weeks of erythromycin or clindamycin treatment (J. J. Leyden, et al., J. Am. Acad. Dermatol. 1987; 16:822-827). Topical nonprescription drugs such as sulfur and salicylic acid are considered less effective. For topical treatment of warts, probably with the exception of salicylic acid, drugs such as bleomycin, 5-fluorouracil, podophyllin and imiquimod require a physician's prescription. Furthermore, at least two or three months of sustained treatment are generally required. Potential serious adverse effects of topical or systemic treatment for both acne and warts are well known. Furthermore, unsightly “permanent” scars are often present after completion of the treatment.
It is important to emphasize here that many reported antimicrobial compounds can kill the microorganisms and “cure” the diseases but often inhibit wound healing (U.S. Pat. No. 5,567,716 by Della Valle et al., Oct. 22, 1996). Furthermore, healing or treatment of a disease, a lesion or a wound may also result in the formation of an unsightly, undesirable scar on the skin (“Webster's New World Dictionary,” edited by D. B. Garalnik, Prentice Hall Press, 1986, pp. 1271) as exemplified in the conventional treatment of acne, warts and herpes simplex.
The above brief review clearly indicates that there is an urgent need to develop a new, novel, simple, rapid, highly safe, highly effective topical treatment of acne and warts without leaving scars behind after the treatment. Ideally, the new drug treatment may not require a prescription, and the same drug can be used to treat both diseases. The present invention is aimed to achieve the above objectives.